Field of the Invention
The present invention relates to network virtualization. In particular, the present invention relates to a method, apparatus, system and computer program product providing a mechanism for improving creation/modification processes for a virtual network in order to ensure reliability of the virtual network and resources used therein.
Related Background Art
Prior art which is related to this technical field can e.g. be found in “Network Virtualization from a Signaling Perspective” by Roland Bless and Christoph Werle, Future-Net '09 International Workshop on the Network of the Future 2009 in conjunction with IEEE ICC 2009, Dresden, Jun. 16-18, 2009, “Implementing Network Virtualization for a Future Internet” by P. Papadimitriou, O. Maennel, A. Greenhalgh, A. Feldmann, and L. Mathy, 20th ITC Specialist Seminar on Network Virtualization, Hoi An, Vietnam, May 2008, as well as Request For Comments (RFC) Nos. 4461, 4655, 4657, 5305, 5810 issued by the IETF.
The following meanings for the abbreviations used in this specification apply:    CAA—conjunction allowed active    CAP—conjunction allowed passive    ERO—explicit route object    FORCES—forwarding and control element separation    IP—Internet protocol    NE—network element    PCE—path computation element    PCEP—path computation element protocol    PIP/InP—physical infrastructure provider/infrastructure provider    POP—point of presence    QoS—quality of service    RRO—record route object    RSVP—resource reservation protocol    SERO—subsequent explicit route object    SLRG—shared risk link group    SRRO—subsequent record route object    VNO—virtual network operator    VNP—virtual network provider    VR—virtual resource
In the last years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), broadband networks, and especially the Internet and other packet based networks based e.g. on the Internet Protocol (IP), Ethernet, MPLS/GMPLS (Multiprotocol Label Switching/Generalized Multiprotocol Label Switching) or related technologies and preferably using optical transmission based on SDH/SONET (Synchronous Digital Hierarchy/Synchronous Optical Networking) and/or WDM/DWDM (Wavelength Division Multiplexing/Dense Wavelength Division Multiplexing), or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) communication networks like the Universal Mobile Telecommunications System (UMTS), enhanced communication networks based e.g. on LTE, cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolutions (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN) or Worldwide Interoperability for Microwave Access (WiMAX), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WiMAX Forum and the like are working on standards for telecommunication network and access environments.
Recent technology progress deals with network virtualization, which splits the conventional monolithically owned, used and operated networks into subsets to be used, operated and managed by different, organizationally independent control entities or organizations. Basically, network virtualization is a concept to create logical network resources, e.g. virtual nodes and virtual links, which form a virtual network, from physical resources.
The use of network virtualization promises additional flexibility and offers opportunities for deploying future network architectures. That is, network virtualization enables for the creation of logically isolated network partitions over a shared physical network infrastructure, wherein the network virtualization can be driven by the needs in, for example, an enterprise domain. Furthermore, network virtualization covers network elements and protocols that together maintain a coherent end-to-end view of a virtual network.
Basically, network virtualization is considered in 3 main sections:                Network elements: how is traffic separation and isolation of different virtual networks maintained internal to a network element for the data part and the control part;        Data path: how is traffic separation enforced across a network path;        Control plane: what extensions to protocols are needed to control and manage partitioned resources (access to NEs and between NEs).        
Considerations regarding network virtualization are made, for example, in connection with several projects, for example 4WARD (European-Union funded) and G-Lab (German national funded). Results of such projects introduced, for example, a separation into different roles regarding network virtualization, i.e. a Virtual Network Operator, VNO, role or level, a Virtual Network Provider, VNP, role or level, and a Physical Infrastructure Provider or just Infrastructure Provider, PIP/InP, role or level.
PIP/InP are infrastructure providers, e.g. large companies that own the infrastructure required to enable communication between different locations and which provide end users with access to their networks. Infrastructure providers may also enable the creation of virtual nodes and virtual links on top of and using their own physical resources and provide them to another party.
VNP is a provider which represents an intermediate party between a VNO and the infrastructure providers. This is depicted, for example, in FIG. 2 which shows a diagram illustrating the hierarchical levels of entities involved in a creation (or modification) of a virtual network, as well as the responsibilities thereof, in comparison to a “normal” (or conventional) network. The VNP is capable and equipped, for example, to compose and provide a virtual network slice as requested by a VNO from physical resources of one or more infrastructure providers. It is to be noted that, in the following specification, a VNP and a PIP/InP may be also referred to belonging to a lower provider level (when viewed from the VNO side), or the PIP/InP may be referred to belonging to a lower provider level (when viewed from the VNP side).
The VNO, on the other hand, can install and instantiate a network architecture using the virtual network slice and properly configure it. After the virtual network has been set up, end users may attach to it and use the service it provides. A VNO may provide a service in the virtual network by itself or allow other service providers to offer their services, e.g., an IP-TV service, inside the virtual network.
That is, the VNP is supposed to request and collect virtual resources from a PIP/InP, and to form a whole virtualized network on behalf of a VNO, which in turn operates this virtual network. In that way, the physical resources of a PIP/InP are separated and transformed into virtual resources provided to and managed by a VNP, and configured to form virtual networks finally handed over to VNOs for operation and use. In that way also the control of such virtual resources, even if implemented as shares of the same physical entities, is completely handed over to the virtual network operator using it.
FIG. 1 shows an exemplary example of a general virtual network topology. The virtual network may span various network domains that belong to different PIP/InP networks 1, 2, 3.
End users 4 to 6 can connect to the (virtual) network infrastructure. Within the network domains belonging to the different PIP/InP networks 1, 2, 3, the virtual network can use virtual or physical resources (virtual nodes are indicated by black filled circles, physical (or substrate) nodes are indicated by white filled circles) to create a virtual network via virtual links (indicated by dashed lines) which run over physical links (solid lines) established between respective nodes.
As for conventional networks, the operator of a virtual network is faced with certain requirements related to the quality of service and/or the grade of service provided by his network. Such requirements may, among others, include simple throughput capabilities (bandwidth capacity) with related delay and packet loss limitations, but also extend to parameters like service availability, e.g. measured in a percentage of time, or service reliability, measured e.g. as a probability of a service connection, once established, to be interrupted, and/or specifications for service restoration times in case of interruptions. A plenty of related parameters can be imagined with a lot of different ways to measure and evaluate related performance. Thus the examples listed here may be considered as representative, but in no way the list can be considered as exclusive or exhaustive.
Quality and grade of service related requirements are usually fixed in so called Service Level Agreements, SLAB, between the network operator and its customers and are often furnished with penalties for breach of contract. It is thus essential for a network operator to be able to specify such parameters and to guarantee compliance with related specifications.
Whereas it often turned out difficult for the owner of a physical network to specify and guarantee related SLAB, such agreements in view of parameters like service availability and reliability have been not possible up to now for virtual networks, as no mechanisms to reliably provide such properties and to control related parameters in a virtual network have been known.